For me SKCL Brown > Vintage Blacks. That's also because I enjoy the shorter throw. I feel like the longer stroke of a Cherry MX switch can also exaggerate smoothness to an extent.
Rarity as I've observed:
SKCL Browns > SKCM Neon Greens > SKCM Browns > SKCL Greens >> MX Vintage Blacks
Of course, in terms of rarity, Striped Ambers and Ambers are above them.
I would say that there is a split between pine and bamboo SKCM Greens though. I'd place SKCM Green (pine) as a little MORE rare than SKCL Brown, because pine is seldom seen from DocuTechs.
So it'd be like SKCM Green (pine) > SKCL Brown > SKCM Green (bamboo) > SKCL Cream > SKCM Amber > SKCM Brown > SKCM Cream >
(it starts getting into the common end here. I'd say SKCM Blue next).
The last three are not necessarily rare in my eyes because there seems to be no shortage of 5140 and Apple IIc computers. I rarely see the Bondwell 8T Pro laptops though. The NeXT boards are thinning out, but Canon Typewriters in the AP _50 series always seem to have SKCM Cream as long as the LED indicator is rectangular.
There's also a rare Sharp keyboard that might be full of SKCL Cream, but I'd say in general that the switch is rare to find in an entire board.